A project that enables Pokémon trading between FireRed/LeafGreen and Ruby/Sapphire/Emerald using a single Game Boy Advance (GBA) and an RP2040-based development board (e.g., Raspberry Pi Pico, RP2040 Zero, etc.). This solution eliminates the need for a second GBA or a second game cartridge, making it an inexpensive and straightforward way to trade your Pokémon. Note: While this tool supports trade evolutions, mail attached to Pokémon will not be transferred.
The RP2040 board acts as a spoofed GBA in a link cable connection, simulating the second console during the trading process. The project uses the link cable's multiplayer mode for communication between the GBA and the RP2040.
I really have no idea what I'm doing when I made this but was able to pull it off despite not knowing anything about micro controllers so don't judge my code. If it works it works. ;) Don't try this on GBC otherwise you'll toast RP2040.
Specially thanks to Goppier!